- "We came here with a team of five, just like you. You know, we all made it, which is rarer than you think, believe it or not."
- — Rick Hall

A misfire occurs when a consciousness transfer from the future is not successful. Consciousness transfer requires a precise time, elevation, latitude, and longitude to overwrite a host, and all of these calculations rely on a historical record that may prove inaccurate. When the incoming Traveler consciousness does not arrive at its intended host body it is "killed," by definition.
The transfer is an all-or-nothing proposition: if the T.E.L.L. is correct, the process is unstoppable short of host death mid-transfer. Otherwise, the process fails to start at all, and the transfer is a misfire. A transfer is also considered a misfire if the consciousness arrives at the wrong host but otherwise survives: Traveler 001 downloaded into the body of Vincent Ingram instead of Anthony Corrigan, as history wrongly recorded the latter as being in his office at the time instead of Vincent. (S1E05: Room 101, S2E01: Ave Machina)
Misfires were frequent in the early days of the Traveler program, reaching 30% during the first wave of arrivals. This statistic is not widely known amongst the rank-and-file Travelers, out of concern that the number of volunteers for the program might decrease. (S1E05: Room 101) They have become less common since, likely due to advances in GPS technology providing more accurate T.E.L.L.s. Prior to the year 2001, GPS technology was not sufficiently advanced to provide reliable data to the Director. No Travelers were sent to before this time because misfire rates would have been too high.